1. Field of the Invention
The present invention relates to mill and milling cutters and cutting inserts used thereon, and in particular to a helical cutter system that includes a cutter body with indexable helical cutting inserts.
2. Description of the Related Art
Currently, the use of an indexable insert is not the first choice for small machine tools because the spindles on such small machines produce relatively lower horsepower and torque than larger machine tools. Because current cutting insert designs need more power to cut effectively, small machine tools are typically relegated to using solid end mill cutters and shell end mill cutters. However, solid end mill cutters and shell end mill cutters wear as they lose diameter, and if broken, can be entirely scraped. In addition, the limited size of the cutters that can be used with indexable insert designs may result in a loss of productivity.
The inventor of the present invention has recognized these and other problems associated with end mill cutters, such as solid end mill cutters and shell end mill cutters, which utilize a helical cutting edge geometry.
To solve these problems, the present invention provides an improved cutter body that utilizes an indexable cutting insert design that has at least two indexable cutting edges. High positive axial and radial rake angles of the improved indexable cutting insert design uses less power and torque than conventional inserts, thereby allowing smoother cutting action and increased feed rates that would have previously stalled a smaller machine tool. In addition, the cutting insert of the invention can be used in larger cutters with an increased number of cutting edges to increase productivity on both small and large machine tools. Further, the only scrap is the cutting insert and not the entire cutter body, thereby minimizing production costs as compared to conventional designs.
The present invention comprises an indexable cutting insert that includes a flat back that is held in a mounting pocket of a cutter body. The mounting pocket can be designed for ease of manufacture and repeatability. Stub length tooling may be used for rigid setups and lower cost. The cutting insert is located in the mounting pocket on two outboard walls. The cutting insert is secured to the cutter body by use of a screw in a cross hole fashion. The face of the cutting insert has a helical cutting edge on two sides and can be indexed by rotating the cutting insert approximately 180 degrees. With the use of the cutting insert of the invention, the cutter body has a maximum core diameter for strength and rigidity, thereby minimizing tool deflection and extending the life of the cutter body. The cutting insert of the invention can be used in a variety of milling cutter body designs, such as end mill cutters, shell end mill cutters, or the like.
Various aspects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.